Sie können Bookmarks mittels Listen verwalten, loggen Sie sich dafür bitte in Ihr SLUB Benutzerkonto ein.
Medientyp:
E-Artikel
Titel:
Helicobacter pylori cadA encodes an essential Cd(II)–Zn(II)–Co(II) resistance factor influencing urease activity
Beteiligte:
Herrmann, Lutz;
Schwan, Dorothee;
Garner, Rachel;
Mobley, Harry L.T.;
Haas, Rainer;
Schäfer, Klaus P.;
Melchers, Klaus
Erschienen:
Wiley, 1999
Erschienen in:Molecular Microbiology
Sprache:
Englisch
DOI:
10.1046/j.1365-2958.1999.01496.x
ISSN:
0950-382X;
1365-2958
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>Inactivation of <jats:italic>Helicobacter pylori cad</jats:italic>A, encoding a putative transition metal ATPase, was only possible in one of four natural competent <jats:italic>H. pylori</jats:italic> strains, designated 69A. All tested <jats:italic>cad</jats:italic>A mutants showed increased growth sensitivity to Cd(II) and Zn(II). In addition, some of them showed both reduced <jats:sup>63</jats:sup>Ni accumulation during growth and no or impaired urease activity, which was not due to lack of urease enzyme subunits. Gene complementation experiments with plasmid (pY178)‐derived <jats:italic>H. pylori cad</jats:italic>A failed to correct the deficiencies, whereas resistance to Cd(II) and Zn(II) was restored. Moreover, pY178 conferred increased Co(II) resistance to both the <jats:italic>cad</jats:italic>A mutants and the wild‐type strain 69A. Heterologous expression of <jats:italic>H. pylori cad</jats:italic>A in an <jats:italic>Escherichia coli znt</jats:italic>A mutant resulted in an elevated resistance to Cd(II) and Zn(II). Expression of <jats:italic>cad</jats:italic>A in <jats:italic>E. coli</jats:italic> SE5000 harbouring <jats:italic>H. pylori nixA</jats:italic>, which encodes a divalent cation importer along with the <jats:italic>H. pylori</jats:italic> urease gene cluster, led to about a threefold increase in urease activity compared with <jats:italic>E. coli</jats:italic> control cells lacking the <jats:italic>H. pylori cad</jats:italic>A gene. These results suggest that <jats:italic>H. pylori Cad</jats:italic>A is an essential resistance pump with ion specificity towards Cd(II), Zn(II) and Co(II). They also point to a possible role of <jats:italic>H. pylori</jats:italic> CadA in high‐level activity of <jats:italic>H. pylori</jats:italic> urease, an enzyme sensitive to a variety of metal ions.</jats:p>